Meditation, particularly mindfulness meditation, is one of the most popular Complementary and Alternative Medicine (CAM) therapies for alleviating emotional stress, depression and anxiety that are either primary, or secondary to another health condition. While standardized meditation-based treatment packages like Mindfulness Based Stress Reduction (MBSR) and Mindfulness-based Cognitive Therapy (MBCT) have reliably shown sustained improvements in emotional disturbances and wellbeing, they contain so many different components and practices that the active ingredient cannot be ascertained. Mindfulness is comprised of 1) an attention regulation component, which is thought to be cultivated with focused awareness practice, and 2) an accepting, non-judgmental mental stance, which is thought to be cultivated through open-monitoring practice. This project aims to create separate practice criteria for attention and acceptance-focused meditations, compare their clinical efficacy and investigate their separate mechanisms of action in individuals with clinically significant levels of persistent negative affect and depression. The clinical benefit and mechanism of action of focused awareness (FA) vs open-monitoring (OM) vs a no-treatment (waitlist) control will be examined with a three- armed randomized control trial of these eight week interventions. Outcome variables include negative affect (depression, anxiety, stress) and wellbeing. Hypothesized mediating processes include objectively measured attention, emotion regulation and the basic wakefulness on which they depend. In addition to the research application, the training program includes formal education in 1) meditation-based clinical trials methodology and affective disorders, 2) psychophysiological measurement of attention, emotion, sleep propensity and 3) biostatistical methods related to treatment studies. This training prepares me to meet my long-term objective of becoming an independent patient- oriented researcher. Through formal didactic instruction and strong mentoring from experienced investigators who are leaders in the field, I will develop the requisite tools to shed light on which meditation practices are the most helpful for emotional disturbances and by what cognitive and neurophysiological mechanisms.